The present invention relates to the treatment of the papova-type viral infection and in particular to a method and pharmaceutical product for the treatment of warts, including common warts (verruca vulgaris) and plantar warts.
Papova viruses are a group of DNA-containing animal viruses that produce epithelial tumors, the best known of which is the common wart (verruca vulgaris). Characteristically, the tumor is small, firm and rounded with an elevated horny surface. Depending on the particular type, warts may occur singularly or there may be numerous lesions that coalesce to cover an area. Such lesions are cosmetically undesirous and often can be cosmetically disabling and painful. For example, plantar warts are small, deep seated, firm hyperkeratotic lesions, which are commonly found on the soles, hands and knees. When they are situated on pressure-bearing areas, such as the plantar aspects of the feet, they may be painful and cause difficulty in walking. Plane warts are flesh colored, slightly elevated, polygonal lesions that undersirably intrude upon the face and the back of hands. Finally, genital warts (condylomata acuminata) are flesh colored, pedunculated or filiform lesions that occur during the sexually active years and often cause discomfort and irritation in the genital areas.
Warts are a very common viral infection throughout the world that equally affect both sexes. They may be transmitted by either direct or indirect contact and by auto-inoculation. Genital warts are transmitted by sexual contact. Occasionally, some warts will spontaneously resolve within a few months of developing; others, however, persist for years, spreading from one site to another. The average duration of untreated warts is approximately two years. Genital warts, on the other hand, are often resistant to treatment and have a high relapse rate.
Wart treatment methods vary depending on the location and number of the lesions, the degree of associated discomfort and the possibility of cosmetic disability. The success of the treatment varies from method to method. For example, the cytotoxic agent podophyllin used in a 25% solution is used to treat anogenital warts. The podophyllin solution is applied to the infected area and removed about six to eight hours later; Vaseline must be used to protect the surrounding skin. An alternative podophyllin method consists of applying a 15% podophyllin ointment under occlusive plaster to pared periungual warts. This treatment method persists for about six to about eight weeks, with the plaster being changed every three to four days. Neither the 25% podophyllin solution nor the 15% podophyllin ointment can be used on pregnant individuals. Additionally, some patients develop a severe reaction to podophyllin, requiring termination of the treatment.
Cryotherapy, using liquid nitrogen or carbon dioxide snow, is another wart treatment method that is about 70% effective. The duration of freezing depends on the location and size of the wart and can result in some discomfort. If the treatment is successful, the wart usually disappears within two to three weeks; it is not uncommon that repeat treatments are necessary, with longer periods of freezing.
The most common and effective treatment for warts is curettage and cautery. This method, however, is painful and requires local and sometimes general anaesthesia. Surgical removal of warts and radiotherapy, on the other hand, are not recommended. Nitric acid and trichloracetic acid applied with care to pared warts are additional alternative treatments.
Probably the least effective wart treatment involves applications of a salicylic acid solution, ranging in concentration from about 3% to about 10%. Applied daily for about one month, salicylic acid has a low cure rate and usually only succeeds in improving the cosmetic appearance of the wart.
My U.S. Pat. No. 4,987,127, describes the beneficial effects of using acetylsalicylic acid to successfully treat outbreak episodes of herpes simplex and related viruses. Acetylsalicylic acid is a well known drug, available as an over-the-counter pharmaceutical product in the United States. Acetylsalicylic acid is most commonly employed in an ingestible form for analgesic purposes. Acetylsalicylic acid has also been used as a surface supplied analgesic.
The Nitardy patent, U.S. Pat. No. 195,945, suggests the use of acetylsalicylic acid in an ethyl ether and oil base for application to mucous membranes. The patent further suggests a synergistic action between acetylsalicylic acid and ethyl ether.
The Putt patent, U.S. Pat. No. 2,056,208, discloses that acetylsalicylic acid is known for application to mucous membranes of the mouth. The Putt patent also discloses the application of a liniment, including acetylsalicylic acid, to unbroken skin as a liniment for the treatment of inflammation or pain and to provide an analgesic effect. This patent further teaches that in water, acetylsalicylic acid rapidly breaks down to salicylic acid and acetic acid. The rapid breakdown of acetylsalicylic acid is considered undesirable by Putt who suggests the need to use acetylsalicylic acid in a liquid form which does not allow a degradation or breakdown during the time required for absorption through the skin. The particular liniment disclosed is 30 grains in 1 ounce of glycerol oleate or other "unctuous base." The patent further discloses testing for absorption of acetylsalicylic acid by a ferric chloride reaction with any acetylsalicylic present in the urine and by fluorescence of skin which has absorbed acetylsalicylic acid.
The Campbell patent, U.S. Pat. No. 3,119,739 discloses the use of a composition, including acetylmethylsalicylate, for pain relief and as an anodyne agent. The patent includes the statement that "it should be understood in no sense be regarded as a curative agent for the basic cause of the pain." The acetylmethylsalicylate is used as 1-20% mixture in an inert pharmaceutical carrier. Solvents for the acetylmethylsalicylate are preferred as the pharmaceutical carrier but suspensions or emulsions may also be used. Examples of suitable inert pharmaceutical carriers are ethanol, isopropanol and polyethylene glycol. The mixture is useful for treating insect bites and allergic reactions.
The prior art has neither taught nor suggested the use of externally applied acetylsalicylic acid as a treatment for papova-type viral infections, despite prior art disclosing the use of acetylsalicylic acid and related compounds such as methyl salicylate and acetyl methyl salicylic acid as analgesic and anti-inflammatory agents for both internal and external application. To the contrary, the prior art has taught away from pharmaceutical preparations including both acetylsalicylic acid and water because of the fear of rapid degradation of the acetylsalicylic acid component into acetic acid and salicylic acid. Salicylic acid has proven to be an ineffective treatment for epithelial tumors associated with the papova-type virus.